1. Field of the Invention
The invention relates to a method for surface texturing of workpieces, such as molds for plastics processing or erosion electrodes for producing molds, and to a workpiece.
2. Description of Related Art
In order that plastic molded parts have a decorative appearance and/or do not show scratches, they often have a textured surface. The advantages of texturing are not only esthetic. Minor surface flaws which can occur in the molding process are hidden by the texture. Surface texturing can be carried out not only on injection-molded parts, but on virtually any part produced by a molding process.
Suitable tools for plastics processing for producing such molded parts are, for example, injection-molding molds, blowing molds, compression molds, vacuum molds, foaming molds and pressure-casting molds. In order to form the molded parts with a textured surface, the texture must first of all be mapped as a negative pattern onto the corresponding surface of the tool. In addition to blasting techniques, galvanization, photochemical etching and electrochemical dissolving are known in order to map the structure into the tool surface. These methods are described, for example, in "Werkzeugbau fur die Kunststoff-Verarbeitung" [Tool construction for plastics processing], Dr.-Ing. Klaus Stoeckhert, 3.sup.rd Edition, Carl Hanser Verlag, pages 392 to 402 and in "Anleitung zum Bau von Spritzgie.beta.werkzeugen" [Instructions for constructing injection-modling mods], Georg Menges, Paul Mohren, 3.sup.rd Edition, Carl Hanser Verlag, pages 50 to 70.
All the above methods have at least the disadvantage that they are highly complex, tedious and costly. A further disadvantage is that the known methods are environmentally damaging and, in such cases, may no longer be carried out, for example, in Germany due to strict environmental regulations. The necessary transport of products made by these method from other countries represents a further impact on the environment.
For example, photochemical etching also has the further disadvantages that multistage designs can be produced only by repeating the etching process a number of times. Leather grains, for example, cannot be reproduced realistically in the desired manner. Furthermore, the etched structures frequently have sharp edges, so that subsequent blasting with a suitable material, for example glass balls, is required. This requires considerable experience in order to obtain satisfactory results from the etching process. A further disadvantage of this method is that it requires a homogeneous structure and homogeneous hardness of the material to be processed.
The facilities for the process of electrochemical machining (ECM) are very expensive and are therefore suitable only for large batches of workpieces with the same geometry. It is also disadvantageous that the process requires a considerable amount of know-how.